Link aggregation technology is known as a technology for improving the throughput of communication. The link aggregation technology is a technology in which a plurality of communication links that are usable for communication are prepared between the transmission apparatus and the reception apparatus, and a communication link for transmitting data from the transmission apparatus is switched among the plurality of communication links in accordance with the usage state of each communication link, thereby improving the throughput of communication. Then, data transmitted from the transmission apparatus is transmitted in accordance with a protocol such as Transmission Control Protocol (TCP) or User Datagram Protocol (UDP).
When the link aggregation technology is used, packets are, in some cases, delivered to the reception apparatus in a different order than that in which they were transmitted from the transmission apparatus, because of a difference in communication performance, such as communication speed or communication delay, among communication links. Then, when the link aggregation technology is applied to TCP, this disorder of packets may lead to TCP retransmission control and so forth.
Note that there is a known technique in which the delay difference among wireless communication schemes in a wireless system section is measured for each wireless communication scheme by using probe packets such as ping packets, and all the packets transmitted by a wireless communication scheme with a small delay time are delayed by a time period corresponding to the delay difference of this wireless communication scheme, so that the disorder of packets is avoided. Also, a technique in which the distribution of delay times of a plurality of packets transmitted over an IP network is recorded, and packet transmission times are calculated is known.
Japanese Laid-open Patent Publication No. 2011-135145 and International Publication Pamphlet No. WO 2006-070471 disclose examples of the related art.